I just discovered an enormous box of OLD paperbacks in the garage. Beautiful Sci-fi covers from the 50's. I want to share them with anyone who may be interested in them. Otherwise hubby will insist I pitch them. Aaaaack! the thought makes me shudder. Thought I'd put a post on the bazzar 5-1 maybe 10 for 1 if they are light enough. Is there any reason I shouldn't put up a post as long I make it plain that they smell musty and are drying with age?

You can advertise them in the Bazaar and ask for credits for them whether or not they are postable.

The thing you can't do is post them to your bookshelf if you think they might be unpostable.

Any that you think might be unpostable should not be posted to the PBS site, instead you can just make a list of them in your Bazaar thread and offer them that way. (Let people read the list and see what they might want instead of ordering the unpostables from your bookshelf, which would be against the rules).

Just make sure to describe the condition well so people know what they are getting.

Musty isn't against the rules (uless you think they might be moldy), and aged isn;t against the rules either. But some people will be bothered by musty whether or not it is technically postable, so I woudl just make it clear what the condition of your "deal" books is.

If the covers are desirable, post scans. I'm sure someone will want them.

Many of those old sci-fi books are collector items, especially the covers. Our semi-annual library sale always has them in a special section, each individually packed in plastic sleeves, and charges more for them than other sci-fi books.

I agree that Book Bazaar would be just fine as long as your description of their condition is accurate.

You could also offer them in the red thread at the top of the Science Fiction genre forum.  I would only offer them in one place -- either the Bazaar or the SF forum, but if you offer them in the Book Bazaar, you could mention your Bazaar post in the Science Fiction forum.